Superheater



G. P. DRAVO I Jul 10, 1923..

SUPERHEATER Original Filed July 5, 1

2 Sheets-Sheet 1 m H l Patented July 10, 1923.

GEORGE P. BRAVO, F MILWAUKEE, WISCONSIN.

OFFICE SUPERHEATER.

Application filed July 3, 1919, Serial No. 308,568. Renewed October 25, 1920. Serial No.419,4.-88.

To all whom it may concern:

Be it known that I, GEORGE P. DRAVO, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in Superheaters, of which the following is a specification,

reference being had to the accompanying drawing, forming a part thereof.

This invention relates to superheaters of the type shown inUnited States Letters Patent No. 1,185,185, issued to me May 30, 1916.

The main objects of the present invention are to facilitate the flow and maintain a substantially constant or uniform velocity through the apparatus of steam or other fluid to be superheated; to evenly distributethe supply of steam or other fluid to the several sections or parts of the superheater; to simplify the connections of the superheater with a boiler or other source of fluid; and generally to improve the construction and operation of superheaters of this class.

It consists in the construction, arrange ment and combination of parts as hereinafter particularly described and pointed out in the claims.

In the accompanying drawing like characters designate the same parts in theseveral figures.

Figure 1 is a side elevation of a superheater embodying the invention as installed in connection with a boiler and boiler setting terially affect its principle and mode of op eration, to boilers and boiler settings or furnaces of various types, and to independent heaters apart from boilers.

In Figs. 1 and 2.an ordinary horizontal return flue boiler 1, is shown diagrammatically, and in Fig. l apart of the boiler fur-,

nace or setting is shown, 2 designatingthe bridge wall of the furnace, and 3 a heating chamber at the rear end of the boiler.

The superheater in its simplest or elemental form, consists of a heating tube, as 5, which has a steam inlet connection at one end with the boiler and an outlet connection at the other end, and is exposed in the heating chamber of the boiler furnace or of an independent heater, and'of a perforated core pipe, as 6, supported axially within the heating tube and forming therewith an annular passage.

The superheater usually comprises a number of such units, which may be arranged and connected in various ways for example substantially as shown in the drawing.

The tubes 5 are connected at the inlet end with a heater 8, in communication with an inlet chamber 9' formed therein and provided with an inlet passage 10, which is connected as shown in Figs. 1 and 2, with the boiler 1 or source of saturated steam by apipe 11. The core pipes 6 are closed at their lower ends adjacent the outlet ends of the tubes 5 and are held at their closed ends'in' axial alignment with the tubes by cent'er ing pins 12. At their lower ends the tubes 5 are separately connected by coupling headers 13 with the lower ends of like or similar heating tubes 14, forming inefi'ect extensions of the tubes 5 and arranged paralleltherewith. The tubes 14 are connected at their upper ends with the header 8 in communication with an outlet chamber 16 formed therein and provided with an outlet passage 17 with which the outlet or delivery pipe 18 for superheated steam is connected, as shown in Figs. 1 and 2.

For convenience in assembling the parts of the superheater, the headers may be constructed substantially as shown inFigs. 3: and at. The header 8 is formed in the upper side overthe inlet and outlet chambersQ' and 16, with an opening which is normally closed by an arched cover plate 20, detachably fastened, as by bolts, with an inter-' posed gasket to the top wall ofthe header. The coupling headers 13 are formed in the under side in alignment with the tubes 5 and 14 with openings, which are normallyclosed by removable tapered caps 21 fitted therein.

The heating tubes 14 are preferably like the tubes 5, provided with perforated core pipes 23.

One member of each unit of the superheater is reduced in diameter towards or adjacent one end to increase the size and capacity of the annular passage between the members in the direction of steam flow, thereby tending to maintain a substantially constant or uniform velocity and even distributionof the steam through the core pipe and surrounding annular passage.

As shown in the drawing, the perforated core pipes are made of smaller diameter at one end than the other, while the heating tubes are of the same diameter from end to end. The reduction in diameter of the core pipes may be accomplished by making the pipes in sections of diminishing diameter, as shown at the left in Fig. 3 or by. gradually tapering them, as shown at the right in the same figure.

At their larger and open inlet ends the core pipes 6 are threaded in tapered bushings 25, which are fitted in the upper inlet ends of the heating tubes 5 and are formed in the outer side with notches or grooves 26, for admitting a portion of the steam to be heated into the annular passages between the heating tubes and core pipes. These notches or grooves forming restricted inlet openings into the annular steam heating passages, are of increasing size or area away'from the inlet 10 into the chamber 9, as shown in Fig. 1, to evenly distribute the steam admitted from said chamber directly into the annular passages between the heating tube and. core pipes.

As shown in Figs. 3 and 4, to securely hold the bushings and core pipes in place, the bushings may be formed or provided with bails or arched cross pieces 28, centrally suspended or supported by threaded stems or rods 29, adjustably fastened by nuts in a plate 30, which is bolted or otherwise fastened to'the header 8 over the inlet and outlet chambers 9 and 16 therein and underneath the cover plate 20.

The centering bushings 32 at the lower ends of the core pipes 23, may be of polygonal form, such as hexagonal nuts, threaded on the pipes, the flat faces of the bushings= or nuts forming restricted inlet openings into the annular passages between the tubes and pipes. At their upper ends the pipes 23 may be closed, as shown in Fig. 3,

by plugs34, threaded therein and suspended or supported like the bushings 25, by stems or rods 35, from the plate 30.

The lateral openings or perforations 37 in the core'pipes are preferably arranged spirally, as shown in Fig. 3, to impart a whirling movement to the steam in the annular passages between the core pipes and heating tubes and to insure intimate contact of the team and entrained water as it flows through said passages, with the heated walls thereof.

In the operation of the superheater constructed and connected with a boiler as shown in the drawing, steam passes from the boiler 1, through the pipe 11 and passage 10 into the inlet chamber 9 of the header 8, from which it flows freely into the larger open ends of the core pipes 6 and through the restricted openings 26 in the bushings 25 into the annular passages between the core pipes and heating tubes 5, the restricted supply of steam to said annular passages being evenly distributed between the several units of the heater bythe increased size of the openings 26 from the inlet passage 10 towards the ends of the header. The throttlin or restriction of the supply of steam to the annular passages, produces and maintains a somewhat lower pressure in said passages than exists in the core pipes, causing the steam to issue in radial jets from the core pipe through the lateral openings 37 into the annular passages against the surrounding walls of the hot tubes 5.

The reduction in diameter of the core pipes 6 towards their closed ends and the corresponding enlargement of the annular passages towards the outlet ends of the tubes 5, maintain a substantially uniform velocity of the steam in its flow through said core pipes and annular passages.

From the tubes 5, steam passes through the coupling headers 13, freely into the lower and larger open ends of the core pipes 23 therein, and through the restricted openings around the bushings 32 into the lower ends of the annular passages between said tubes and pipes. From the core pipe 23, in which a slightly higher pressure is maintained than inthe annular passages around them, the steam issues in jets through the openings 37 into said passages, in which it is mingled with the steam entering through the restricted openings around the bushings, and is still further heated by contact with the hot walls of the tubes. The superheated steam discharged freely from the upper and larger open ends of the annular passages into the chamber 16 in the header 8, flows therefrom through the outlet passage 17 into the service or delivery pipe 18.

The reduction in the diameter of the core pipes 23 towards their closed ends, and the corresponding enlargement of the annular passages around them, operate like the core pipes 6 of reduced diameter towards their closed ends and the annular passages of enlarged area towards their outlet ends be tween them and the tubes 5, to maintain a substantially constant velocity of the steam without material obstruction to its flow through the superheater.

Various changes in the construction and arrangement of parts of the superheater in its adaptation to boilers of different sizes and types and to varying conditions may be made without departure from the principle and scope of the invention as defined in the following claims.

I claim: 7

1. In a superheater the combination of an inlet chamber, a heating tube connected at one end with said chamber and having an outlet at the other end, a perforated core pipe extending from said chamber with which it communicates at one end into the heating tube with which it forms an annular passage of enlarged size adjacent the outlet end of the heating tube, and a bushing interposed between the heating tube and core pipe adjacent its inlet end and formed with an opening from said chamber into said passage.

2. In a superheater, the combination of an inlet chamber, a heating tube connected at one end therewith andhaving an out let at the other end, a core pipe extending from the heating chamber axially into the heating tube and forming therewith an annular heating passage, said core pipe being closed at its other end and formed between its ends with lateral openings into the annular passage, and a bushing between the inlet end of the heating tube and core pipe having an opening from the inlet chamber into the annular heating passage.

3. In a superheater the combination of a header having an inlet connection, a number of heating tubes connected and communicating at one end with the header,

a core pipe communicating at one end with the header and extending therefrom axially into each of the heating tubes and forming therewith an annular heating passage, and bushings interposed between the heating tubes and core pipes at their inlet ends and formed with openings from the header into the annularpassages, said openings increasing in area away from the inlet connection of the header.

4. In a superheater the combination of a header formed with inlet and outlet chambers and connections, heating tubes connected at one end of each with the inlet and outlet chambers respectively and cross connected at the other end with each other, perforated core pipes arranged axially within the heating tubes and forming therewith annular passages, said pipes being open at the ends adjacent the inlet ends of the heating tubes and closed at the other ends adjacent which they are of reduced diameter, and centering bushings between the inlet ends of the heating tubes and core pipes formed with openings into the annular passages.

In witness whereof I hereto afiix my signature.

GEORGE P. DRAVO. 

